It lasts one hour like the Wings of Flying, and can only be used once ever. The potion of flying gives a fly speed equal to your walk speed the same as the Winged Boots do. The next item I found was the potion of flying. 10 times more than the Winged Boots or the Broom. They are worth 5,000 gold, just like the Wings of Flying. You can't use it for longer than 10 minutes on end without returning to the ground. It has a similar weight limit to the Broom. It can never move you more than 20 feet off the ground or more than 20 feet up or down at a time. Levitate moves you straight up or down only. These boots let you use levitate as the spell at will. The next item I found was the boots of levitation. They are worth 5,000 gold, 10 times what the boots or broom are worth. At most, it's definitely not better than either the Broom or the Boots. The higher move speed will occasionally pay off, but usually the ability to fly whenever you want will win out in terms of practical utility. Again, a pretty powerful item, but probably less useful than either the Broom or the Boots for most practical purposes. The Wings give you a fly speed of 60 feet for one hour but then require a 1d12 hour cooldown period after each use before they can be activated again. Right under the Winged Boots are the Wings of Flying.

Yet both the Boots and the Broom are uncommon, they only cost 500 gold, pretty much any adventurer who decides they want one should be able to get their hands on one if they really want to. If the other side also has no good ranged attacks the flying team more or less wins automatically. Both are clearly very powerful, if you've got two sides in a combat one of which can fly and one of which can't the flying side has a huge advantage.

The Boots give a fly speed equal to your walking speed for 4 hours per day divisible into 1 minute chunks while the broom gives you a flat 50 foot fly speed all day long, decreasing to 30 feet if you are particularly heavy. Among the first I came across were the Winged Boots and the Broom of Flying. There are a few items which give the ability to fly in the 5e DMG. The price tables below have been compiled into an excellent pdf by Inconnunom.

Scroll of lightning bolt 5e cost